Excavator dipper door



Feb. 21, 1956 Filed March 27, 1952 w. s. BUI-QDICK ET AL 2,735,559

EXCAVATOR DIPPER DOOR 2 Sheets-Sheet l IN V EN TORS y M Q KMZ M Feb. 21, 1956 w. s. BURDICK ET AL 2,735,559

EXCAVATOR DIPPER DOOR Filed March 27, 1952 2 Sheets-Sheet 2 INVENTOR 23 W1 1 M 5 BY Q- W/I M United States EXCAVATOR DIPPER DOOR Will S. Burdick, Wanwatosa, and Karl Schneider, Greenfield, Wis, assignors to Harnischfeger Corporation, Milwaukee, Wis, a corporation of Wisconsin Application March 27, 1952, Serial No. 278,918 2 Claims. (Cl. 214-145) the hinge straps through yieldable non-metallic connections.

The digging stroke of an out-stroke shovel is performed by drawing in the hoist cable that runs upwardly and outwardly from the shovel cab to the boom point sheave and hence downwardly to the dipper where it is usually passed about a padlock sheave attached to a hoist bail at the top of the dipper and then upwardly to an anchored connection with the boom. The upward swing of the dipper resulting from drawing in the hoist cable describes an upward arcuate digging movement to cause a cutting motion through the soil. The cutting by the leading edge of the dipper peels and breaks away the soil causing it to tumble and drop into the dipper that is closed at the bottom by a door latched in position. A rocky soil, or one that breaks oil into large aggregate components, will impart sudden severe impact blows to the door as it tumbles or drops into the dipper. Further jarring impacts are often delivered to the door when closing the same against the bottom of the dipper body.

The load stresses due to such jarring impact blows are widely variant in value and the peak values occur somewhat infrequently. Nevertheless, localized values of stress reach extreme values for the more severe blows and are consequently largely determinative of maximum door life, rather than the normal loading. stresses of fre quent repeated nature. While the impact blows are delivered to the upper door face maximum stress may occur in areas that are quite remote from the point of impact. A cushioning that would affect a reduction in the stresses throughout the door and its supporting parts would therefore be desirable for minimizing premature breaks and ruptures that otherwise shorten dipper door life.

In the all welded dipper and dipper door type of construction the particular consideration of peak stress values is of great importance. Such construction does not normally allow for sufficient degree of yieldability to cushion peak impact loads and in the course of welding the fabricated structure locked in stresses are often created within the apparatus. Such locked in stresses in conjunction with load Stress frequently set up peak values greater than otherwise would be encountered.

it is an object of this invention to provide a dipper door with mounting connections that yieldably cushion the door to effect a reduction of stress upon being struck a sudden sharp impact blow such as is apt to be delivered during a digging stroke.

It is another object of this invention to mount a door on hinge straps that are pivoted to the dipper proper with a mounting that separates the door from the straps through a non-metallic connection.

It is still another object of this invention to provide atent in a mounting connection precompressed resiliently yieldable bushings that encircle fastening pins for the dipper door and that resiliently compress to permit relative shift of the door and straps in either longitudinal or transverse direction.

These and other objects and advantages of this invention will appear in the description to follow. In the description reference is made to the accompanying drawings which form a part hereof and in which there is shown by way of illustration and not of limitation one specific form in which this invention may be embodied.

In the drawings:

Fig. l is a side view in elevation of an per in which this invention is embodied,

Fig. 2 is a bottom plan View of the dipper door and the hinge straps therefore shown in Fig. 1,

Fig. 3 is a fragmentary view in section of the dipper door and a hinge strap viewed through the plane 3-3, and

Fig. 4 is a side view in section of the dipper door viewed through the plane 4-4.

Referring now to the drawings, there is shown in Fig. 1 a four sided dipper body 1 that is open both at the top and the bottom. The dipper body may be of any suitable construction and for mounting has a pair of bail hinges 2 and a pair of dipper stick pin brackets 3, one of each of which is shown. A hoist bail 4 extends between and is pinned to the bail hinges 2 and the end of a dipper stick 5 is pinned between the pin brackets 3. To hold the dipper body 1 rigid with respect to the dipper stick 5 a brace link 6 is pinned at one end to the dipper stick 5 and at the other end to a bracket '7 that extends rearwardly from the lower margin of the rear of the dipper body 1. Also projecting rearwardly from the dipper body 1 are two pair of door hinges 8, one of which is shown. At the front and bottom of the dipper body 1 is a door latch keeper 9.

A dipper door 10 is pivotally mounted upon the dipper body 1 by a pair of hinge straps 11 and 12 that are each respectively pinned between a pair of the door hinges 8. The door 10 may therefore be swung into closed position against the bottom of the dipper body 1, or into open position to expose the open bottom of the dipper body 1, as is shown in phantom in Fig. l. The door 10 has a floor panel 13 that extends across the bottom of the dipper body 1 to fully enclose the same upon the door 10 being swung into closed position. To impart necessary rigidity and strength to the floor panel a fabricated front box channel 14 extends transversely along the underside of the forward margin of the floor 13. A second fabricated box channel 15 extends transversely and approximately in the center of the underside of the floor 13. .A rear fabricated channel member 16 of triangular cross section is extended along the rear margin of the underside of the floor 13. Each of the channels 14, 15 and 16 excavator dipis welded to the floor plate 12 to form a one-piece integral dipper door.

A retractable door latch 17 is provided to engage and to be retained by the door latch keeper 9 when extended forwardly into its normal position, as shown in Figs. 1 and 2. The door 10 is then maintained in closed position and upon a rearward retraction of the latch 17 the door It will swing open from either its own weight or that of a load in the dipper. To return the door 10 to closed position the operator swings the dipper stick 5 in pendulum fashion and the latch 17 that is urged into normally extended position engages the keeper 9. The latch 17 is retracted from extended position by a latch lever 18 hinged at one end to a bracket 19 and pinned at a medial point to the rearward end 20 of the latch 17. The lever 18, in turn, is operated by a latch cable 21 secured to the end of the lever 18 opposite the bracket 19.

Apair of crosswise spaced parallel hinge strap mounting plates 22 and 23 that extend fore and aft along the underside of the floor panel 13 are disposed to one side of the door center line. A second like pair of mounting plates24 and25 are disposed to the opposite side of the door center line. The hinge strap 11 is placed between the two plates 22 and 23 and the hinge strap 12 is similarly placed between the second pair of plates 24 and 25. Each of the straps 11 and 12 is then joined to the door 10 by a pair of pinnedconnections.

One of the pinned connections is'shown in section in Figs. 2 and 3. A pair of resilient non-metallic bushings 27 and 28are inserted within an opening 26 in the hinge strap 11. The bushings 27 and 28 are'inserted from opposite sides of the hinge strap 11 and abut one'another to completely line the opening 26. Flanged heads 29 and 30 that form a portion'of the bushings 27 and 28, respectively, extend sidewardly beyond the strap 11 and seat between the inner faces of the mounting plates 22 and 23and the strap 11 so as to separate the strap 11 from the plates 22 and 23, while still providing a solid crosswise connection. A pin 31 is extended through the bushings -27 and28 and through a second pair of bushings 32 and 33 that are set in the mounting plates 22 and 23. Bushings 32'and 33 are shown as being of metallic material. Pin 31 also extends through a pair of strengthening plates 34 and 35 that are disposed against the outer faces of the plates22 and 23.

In an identical manner the forward end of the hinge strap 11 is secured by means of a pin 36 and resilient bushings 37 and 38 to the mounting plates 22 and 23. Also, the hinge strap 12, that is placed between the mounting straps 24 and 25, is secured in position by pins 39 and 40 and associated resilient bushings.

An car 41 is formed on each hinge strap 11 and 12 near the endspivoted to the dipper body 1 and disposed between each of the ears 41 and the-dipper stick 5 is one of apair of friction toggles 42 that complete the dipper assembly. Each toggle 42 is comprised of a toggle arm 43 pinned at one end to toggle arm 44pinned at one end to the dipper stick 5 and at the other end to the arm 43 to form a toggle knee. The toggles 42 act to retard swinging movement of the door ltl by means of pivotal friction developed at the knee of the toggle. As the angle between the arms 43 and varies the frictioncorrespondingly varies. Such friction toggles do not form a part of this invention, their purpose being to minimize only the impact of the door 10 upon closing with the dipper body 1. Such an arrangement has heretofore been enjoyed in various dipper constructions.

The resilient bushings, such as 27 and 28, may be formed of any suitable material, such as a natural rubber, that is yieldable and sufliciently resilient to retain shape and not to tare an appreciable permanent set after a period of use that is subject to frequent impact. It has been found desirable to preload the resilient bushings by subjecting them to a state of permanent compression in the assembly of the apparatus. This may be accomplished by providing an outer diameter for the bushings that provides for a snug fit when inserted in the hinge straps and then employing an innerdiameter less than the diameter of the associated mounting pin. By tapering the leading end of the pin and lubricating it with a substance not injurious .tothe bushing material it may be worked into place, thus subjecting the bushing to a state of precompression.

The compressedportions of the bushings that are disposed between the mounting pins and the walls of the openings within the hinge straps are reduced in volume from that of normal size. The elastic material of which one of the ears 41 and a second the bushings are composed will tend to flow or be dis-' placed from the regions of reduced volume into the spaces between the respective hinge strap side faces and the hinge strap mounting plates. The flanged bushing heads, such as 29 and 30, act as constraining rings that oppose such tendency to be displaced. This confining action of thebushing heads is enhanced by the bevel of the inner bush-- ing faces and the abutting bevel of the hinge straps. The bevel provides for a resistance to radial expansion of the bushing heads. The outer cylindrical surface of the flange heads, however, are not contained or restrained from radial expansion, thus there may occur a limited displacement of the compressed bushing material. Through precompression the forces that act to align the pins and hinge straps with respect to one another are of enhanced value and a shift in alignment from repeated impacts is less likely to occur. It has been found that a compression of five to eight per cent by volume gives desirable results.

In the practice of this invention the dipper door 10 is joined with the hinge straps-11 and 12, and hence the'dipper 1, through the medium of a cushioning connection. It is at the junction of the door 10 and the hinge straps 11 and 12 that stresses often tend to reach peak values and the yieldable structure of this invention effects a material reduction in peak values at this point, as well as in other portions of the door 10. Thus, a cushioning provided at the underside of the door panel provides for lower peak stresses at both the points of impact and other areas that are prone to encounter peak stresses.

We claim:

1. In an excavator dipper having a door panel and a hinge strap, the improvement in a connection between said panel and strap comprising means forming a strap receiving channel and including substantially parallel spaced flanges mounted on said panel and laterally embracing said strap, the thickness of said strap being less than the spacing between channel flanges, said strap and strap flanges being provided with aligned pin openings and a pin therein for interconnecting said strap and flanges, the external diameter of the pin being less than the diameter of the strap opening, a resilient bushing ensleeved on the pin and disposed between the pin and the wall of the strap opening for cushioning door panel and strap impact shocks transmitted in a direction transverse to the axis of the pin, and resilient end cushions of larger diameter than the bushings aforesaid between the sides of the strap and the said flanges to cushion door panel and strap impact shocks transmitted in a direction aligned with the axis of the pin.

2. The device of claim 1 in which the said resilient bushing is radially precompressed, the sides of the strap being tapered toward the strap opening and said end cushions being correspondingly tapered whereby the tapered portion of said end cushions are radially confined, the portions of said end cushions beyond said tapered portions being y relatively free for radial displacement.

References Cited in the tile of this patent UNITED STATES PATENTS 1,739,270 Thiry Dec. 10, 1929 1,766,255 Mullally June 24, 1930 1,944,949 Ratkowski Jan. 30, 1934 1,981,267 Heffelfinger Nov. 20, 1934 2,110,701 Farmer Mar. 8, 1938 2,180,348 Daniels Nov. 21, 1939 2,261,955 Browne Nov. 11, 1941 2,299,926 Phelps Oct. 27, 1942 2,308,967 Kuss Jan. 19, 1943 2,335,352 Murtaugh Nov. 30, 1943 2,366,860 Kraft Jan. 9, 1945 2,561,518 Larsen July 24, 1951 

